Add 'release' workflow to create a GH release on tags

This should help the conda-forge bot to pick up new releases faster.

.github/workflows/release.yml

@@ -0,0 +1,16 @@
+name: release
+
+on:
+  push:
+    tags:
+      - "[0-9]+.[0-9]+.[0-9]+"
+
+jobs:
+
+  release:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: GitHub Release
+      uses: softprops/action-gh-release@v1